MediaPlayer暫停並播放錯誤

Question

我正在用Java和XML構建Android應用程序。應用程序的用戶必須能夠聽到曲調並暫停播放。所以我製作了一個可以播放和暫停曲調的按鈕。我做了一個函數，其中必須更改ImageView的src。然而Eclipse給我一個錯誤在mp.start()和mp.pause()，它說：「mp不能解決」。

我不知道我現在做錯了什麼，我希望有人能幫助我。

Java代碼：

import android.media.MediaPlayer; 
import android.os.Bundle; 
import android.app.Activity; 
import android.content.Intent; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ImageView; 

public class Level01vraag01 extends Activity implements OnClickListener { 

    int playknopvariable = 0; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.vraaglayout); 
     setupButtonClickListeners(); 
     final MediaPlayer mp = MediaPlayer.create(Level01vraag01.this, R.raw.mcdonalds); 
    } 

    private void setupButtonClickListeners() { 
     ImageView playsoundButton = (ImageView) findViewById(R.id.playsoundbutton); 
     playsoundButton.setOnClickListener(this); 
    } 

    private void klikopplaybutton() { 
     if (playknopvariable == 0) { 
      mp.start(); 
      playknopvariable = 1; 
      playsoundButton.setImageResource(R.drawable.playsoundbutton); 
     } else { 
      mp.pause(); 
      playknopvariable = 0; 
      playsoundButton.setImageResource(R.drawable.pause); 
     } 
    } 

    public void onClick(View v) { 
     switch (v.getId()) { 
     case R.id.playsoundbutton: 
      klikopplaybutton(); 
      break; 
     } 

XML代碼：

<ImageView 
    android:id="@+id/playsoundbutton" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_above="@+id/guessbutton" 
    android:layout_centerHorizontal="true" 
    android:layout_marginBottom="33dp" 
    android:src="@drawable/playsoundbutton" /> 

Answer 1

，因爲我認爲你已經宣佈並在onCreate方法實例化MP和它是不是在klikopplaybutton（）方法進行訪問。

嘗試類似這樣的東西。

public class Level01vraag01 extends Activity implements OnClickListener { 

    int playknopvariable = 0; 
    MediaPlayer mp; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.vraaglayout); 
     setupButtonClickListeners(); 
     mp = MediaPlayer.create(Level01vraag01.this, R.raw.mcdonalds); 

    } 

private void setupButtonClickListeners() 
{ 
    ImageView playsoundButton = (ImageView) findViewById(R.id.playsoundbutton); 
    playsoundButton.setOnClickListener(this); 
} 

UPDATE在您的ImageView的錯誤。

您在您的playsoundButton ImageView對象中發生錯誤，因爲您再次聲明它並在setupButtonClickListeners方法中執行findViewById，並且它在klikopplaybutton方法中不可訪問。

試試這個。

public class Level01vraag01 extends Activity implements OnClickListener { 

    int playknopvariable = 0; 
    MediaPlayer mp; 
    ImageView playsoundButton; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.vraaglayout); 
     setupButtonClickListeners(); 
     mp = MediaPlayer.create(Level01vraag01.this, R.raw.mcdonalds); 

    } 

    private void setupButtonClickListeners(){ 
     playsoundButton = (ImageView) findViewById(R.id.playsoundbutton); 
     playsoundButton.setOnClickListener(this); 
    } 

    private void klikopplaybutton(){ 

     if (playknopvariable == 0){ 
      mp.start(); 
      playknopvariable = 1; 
      playsoundButton.setImageResource(R.drawable.playsoundbutton); 
     }else{ 
      mp.pause(); 
      playknopvariable = 0; 
      playsoundButton.setImageResource(R.drawable.pause); 
    } 

    public void onClick(View v) { 

     switch(v.getId()){ 
     case R.id.playsoundbutton: 
      klikopplaybutton(); 
     break; 
    } 

}